October 23, 2003 – Broccoli sees its content of three antioxidant substances melt when cooked in the microwave, and there is no guarantee that this method of preparation does not have the same effect on other foods.
Spanish researchers have thus discovered1 that when prepared in the microwave oven, broccoli loses, respectively, 97%, 74% and 87% of the antioxidants that have been studied. The best method of cooking would be by steaming, since the losses would then be only 11%, 0% and 8%.
The intense heat generated by the microwave oven would probably be responsible for the phenomenon.
However, it should be noted that this study only looked at raw broccoli. The effect of microwave cooking on other foods, or even its effect on steamed and then “reheated” broccoli, has not been measured.
This study also takes a look at cooking in boiling water. Researchers have found that broccoli cooked this way loses about 66% of its antioxidants, since they are soluble in water. This last conclusion is reinforced by those of another study.1, which reveals that the blanching process that vegetables go through before they are frozen can reduce their antioxidant content by a third. Freezing for only seven days would destroy about 60% of the flavonoids in broccoli.2.
However, since nothing is ever easy, other researchers recently found that cooking in the microwave is the best way to preserve the vitamin C content of broccoli.
Antioxidants are found in many foods, including fruits and vegetables, and are believed to protect the body against cancer and cardiovascular disease.
Jean-Benoit Legault – PasseportSanté.net
From foodsciencecentral.com and The Globe and Mail; October 13 and 17, 2003.
1. The results of these studies are published in the current edition of the Journal of the Science of Food and Agriculture.
2. Vallejo F, Tomas-Barberan F, Garcia-Viguera C. Health-promoting compounds in broccoli as influenced by refrigerated transport and retail sale period. J Agric Food Chem 2003 May 7; 51 (10): 3029-34.
